Application of Two OI Land Surface Assimilation Techniques in GRAPES_Meso
The initial soil water content and temperature significantly influence numerical weather forecasts. The Optimal Interpolation (OI) technique takes into account observation and forecast errors in an objective statistical way and can produce the analyzed soil water content and temperature. The OI_EC and OI_MF, which were developed from the original OI technique, have been used in the operational systems in European Centre for MediumRange Weather Forecasts and in MétéoFrance, but not in the GRAPES_Meso of China. So, we tried to apply the two OI techniques in the GRAPES_Meso. The experiment results of the two seasons in summer and winter show that the accuracy of the simulated 2 m temperature is improved by the use of the two OI techniques, and there is no obvious change in precipitation simulation results. Comparing the results of two OI techniques, we find that the OI_EC coefficients are more reasonable, and the OI_MF method is not suitable for simulating in the low vegetation coverage area.